Invasion of the Butterflies

Eastern Tiger Swallowtails have their day

By Sandra Olivetti Martin

Kathy Mercer’s photo of tiger swallowtails on a giant sunflower.

A butterfly or two is an everyday pleasure.
A dozen or more, a sign you’ve planted well, raising a native garden of plants that bloom in sequence so emergent broods find the food they need to survive.
But an atmosphere thick with butterflies, bushes shimmering with butterflies: What is that?
The Eastern Tiger Swallowtail irruption of summer 2013, according to reports from throughout Chesapeake Country. Eastern Tiger Swallowtails — one of four types of swallowtails common hereabouts — are big showy yellow butterflies striped in black, which also edges their wing perimeter and tails, named for their swallow-like projections.
Females are more beautiful still, with iridescent blue scales and an orange marginal spot on their hind wings. Some females wear charcoal black instead of yellow as their main color.
This discovery makes me think I was wrong in counting black swallowtails among the hundreds of tiger swallowtails that turned my head and sent me running for my camera when I saw them enveloping a big stand of Joe Pye weed on July 31.
Eastern Tiger Swallowtails have the Virginia-Maryland-Delaware Bug Group rippling.
“Is anybody else noticing how many Tiger Swallowtails there are this year? My yard in Bowie is delightfully full of them,” wrote Kevin.
“Yes, big year in southern Delaware for Tiger Swallowtails,” wrote Jason from Abbotts Mill Nature Center in Milford.
“Eastern Tiger Swallowtails are abundant now in central Anne Arundel County where I live. At Governor’s Bridge Natural Area in Prince Georges County, I saw large numbers of Eastern Tigers and Spicebush Swallowtails nectaring on pickerelweed at the edge of the pond there. I saw a few Zebra Swallowtails, too,” wrote Kathleen.
Bay Weekly readers are talking too.
“Taken Friday morning [Aug. 1]. Looking out the window, had to get my camera. Also saw a hummingbird and yellow finch; They were too quick for my camera,” wrote Kathy Mercer, attaching her photo of tiger swallowtail on sunflower.
To what do we owe this splendid show?
Has a brood hatched? Battle Creek Nature Center naturalist Andy Brown tells us that in Chesapeake Country, Eastern Tiger Swallowtails emerge in two or three broods a year, evolving from egg, larvae and pupae to butterfly.
Is the weather fine? Are all the plants they like in bloom at the same time?
Or are we just lucky?
“Yes,” says Sam Droge, who studies insects with the U.S. Geological Survey. “Maybe a remarkable day in their life cycle. It could be any or all of that.”
Many butterflies have very specific tastes, both as caterpillars and as butterflies. Monarch caterpillars depend on milkweed. Black swallowtail caterpillars like things in the parsley family. Tiger swallowtails do their caterpillaring in the tulip poplar trees so abundant in Chesapeake Country, so there’s plenty for them to eat.
As well as Joe Pye weed, butterfly bush and pickerelweed, swallowtail butterflies like all the sunflower family. They like New York ironweed, and they especially like Devils Walking Stick. That big bush, Andy Brown notes, “started blooming within the last week.” Just about the time of the tiger swallowtails invasion.
You can get pretty close to these big butterflies, especially when they’re busy dipping nectar. Look, and you’ll notice many have tattered wings. The delicacy that enables them to fly is also their downfall.
“It’s a rough life for any flying insect,” Droge says. Wear and tear to their wings “dooms most of them.”
But by the time these beauties are dying, their offspring are traveling on the metamorphosis road. Next spring, there will be more Eastern Tiger Swallowtails.